WMS:Basin HEC-1 Cards: Difference between revisions

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[[Image:Edit HEC-1 Parameters.jpg|thumb|470 px|''Edit HEC-1 Parameters'' dialog]]
[[Image:Edit HEC-1 Parameters.png|thumb|470 px|''Edit HEC-1 Parameters'' dialog]]
When a basin is selected in the HEC-1 model, selecting ''HEC-1'' | '''Edit Parameters''' will bring up the ''Edit HEC-1 Parameters'' dialog with the ''Basin HEC-1 Cards'' section active. The following can then be specified:
When a basin is selected in the HEC-1 model, selecting ''HEC-1'' | '''Edit Parameters''' will bring up the ''Edit HEC-1 Parameters'' dialog with the ''Basin HEC-1 Cards'' section active. The following can then be specified:
[[Image:HEC1 Basin Data.jpg|thumb|200 px|''HEC-1 Basin Data'' dialog]]
==Basin Data...==
===Basin Name (KK)===
Each hydrograph station should be identified with a unique name. This name appears as part of the KK record for that station in the input file. The name should not be more than six characters long. By default WMS uses the basin ID number followed by a "B" for the name, but a descriptive name is generally more useful.
===Basin Area (BA)===
When a terrain model is used, basin areas and slopes can be computed automatically using the '''Compute Basin Data''' command from the ''Drainage'' menu of the TIN or DEM module, or the '''Update Basin Data''' command in the ''Feature Objects'' menu of the Map module. Otherwise, areas and slopes must be entered interactively using the topological tree as a map. Areas should be entered in either square miles or square kilometers.


===Base Flow (BF)===
Base flow parameters can be defined for a basin by selecting the ''Enter base flow'' check box. The input parameters for base flow are as follows:


*''STRTQ'' – Flow at the start of the storm in cfs (cms for metric units).
==''HEC-1 Basin Data'' Dialog==
*''QRCSN'' – Flow in cfs (cms) below which base flow recession occurs in accordance with the recession constant ''RTIOR''. In other words, it is that flow where the straight line (in semilog paper) recession deviates from the falling limb of the hydrograph.
*''RTIOR'' – The ratio of the recession flow ''(QRCSN)'' to that flow occurring one hour later (Must be greater than or equal to 1).


==Output Control...==
Dialog is accessed by selecting ''HEC-1'' | '''Edit Parameters...''' in WMS and then choosing '''Basin Data...''' from the ''Edit HEC-1 Parameters'' dialog.
[[Image:HEC1 Output Control.jpg|thumb|400 px|''HEC-1 Output Control'' dialog]]
For each hydrograph station (basin hydrographs, combined hydrographs, and routed hydrographs) different output controls can be specified. This dialog is accessed by selecting the '''Output Control''' button from the ''Edit HEC-1 Parameters'' dialog. Entries which can be defined in this dialog are described below.
===Routed and Combined Hydrographs at Outlets===


In WMS an outlet point is used to represent locations where hydrographs are both combined and then routed. Therefore, if an outlet is selected before choosing the ''Output Control'' dialog, a radio group at the top of the dialog appears to specify whether the options should be applied to the combined or routed hydrograph. If a basin is selected the radio group at the top of the dialog does not appear.
[[Image:HEC1 Basin Data.png|Thumb|200 px|''HEC-1 Basin Data'' dialog]]


===Comment Lines (KM)===
''Basin name''– Each hydrograph station should be identified with a unique name. This name appears as part of the KK record for that station in the input file.


Individual comments can be defined for each hydrograph station. These comments can be used to identify unique characteristics about a particular basin or outlet point. A new comment can be defined by selecting the new button in the ''Output Control'' dialog and then entering the comment in the text entry. When more than one comment card has been defined, the up and down arrow buttons can be used to scroll through the list of comments for that hydrograph station. When using WMS, comment cards always appear directly after the KK cards for each hydrograph station.
''Area'' – Areas should be entered in either square miles or square kilometers.


===Output Control (KO)===
''Basin Descriptor (Optional)'' – Option for more Description of the Basin.


These controls determine what information about a given hydrograph station is written to the HEC-1 ASCII output file. By default the IO record information is used. However, it may be desirable to print out a more (or less) complete summary for individual hydrograph stations.
''Input hydrograph (QI, BI)'' –
*''Direct input hydrograph (QI)'' – This hydrograph can be input by selecting the checkbox.
*'''Define QI''' – Allows for the definition of the direct input hydrograph. Click to open the [[WMS:XY Series Editor|''XY Series Editor'' dialog]].
*''Tape 21 input hydrograph (BI)'' – Select to indicate that the data should be input as a general hydrograph.
*''Tape 22 input hydrograph (BI)'' – Select to indicate that the data should be input as a specific hydrograph.
''Observed hydrograph (QO)'' –
*'''Define QO''' – Allows the definition of the outflow hydrograph. Click to open the [[WMS:XY Series Editor|''XY Series Editor'' dialog]].
Base Flow Parameters – Base flow parameters can be defined for a basin by selecting the ''Enter base flow'' checkbox. The input parameters for base flow are as follows:
*''Enter base flow'' – Select this to enter the defined base flow.
*''STRTQ'' – Flow at the start of the storm in cfs (cms for metric units).
*''QRCSN'' – Flow in cfs (cms) below which base flow recession occurs in accordance with the recession constant RTIOR. In other words, it is that flow where the straight line (in semilog paper) recession deviates from the falling limb of the hydrograph.
*''RTIOR'' – The ratio of the recession flow (QRCSN) to that flow occurring one hour later (Must be greater than or equal to 1).


By default, the option to write a hydrograph to the TAPE22 file is specified. This is the file read by WMS for display of hydrographs. Therefore, this option should only be changed to suppress particular hydrographs.
==''HEC-1 Output Control'' Dialog==
[[Image:HEC1 Output Control.png|thumb|400 px|''HEC-1 Output Control'' dialog]]
Dialog is accessed by selecting ''HEC-1'' | '''Edit Parameters...''' in WMS and then choosing '''Output Control...''' from the ''Edit HEC-1 Parameters'' dialog.


==Precipitation...==
''Comment Lines'' section – Individual comments can be defined for each hydrograph station. These comments can be used to identify unique characteristics about a particular basin or outlet point.
[[Image:HEC1 Precipitation.jpg|thumb|300 px|''HEC-1 Precipitation'' dialog]]
*'''New''' – Select to add a new comment.
Precipitation patterns are assigned to basins by first selecting the appropriate basin(s) and then clicking on the '''Precipitation''' button in the ''Edit HEC-1 Parameters'' dialog. If multiple basins are selected then the defined parameters will apply to all selected basins.  
*'''Delete''' – Select to delete an existing comment.


:'''''NOTE:''''' If no basins are selected, the parameters can be applied to all basins.
''Output Control (KO)'' – These controls determine what information about a given hydrograph station is written to the HEC-1 ASCII output file.
*Print Control (field 1) – controls how the data collected is printed.
**"Use IO record (O)" – Default setting, prints the entire IO record.
**"Print all output (1,2)" – When selected, prints all output.
**"Print input and summaries" – When selected, it will just print input and summaries of the data.
**"Print input data only (4)" – When selected, it will print the input data only.
*Plot Control (field 2) – Section where plots can be controlled.
**"Use IO record (O)" – Plots are dependant on the IO record.
**"No printer plots (1)" – Select if there are no printer plots.
**"Plot hydrograph (2)" – Select to receive output on the plot hydrograph.
*''Plotting Scale (field 3)'' – Section to specify the plotting scale.
*''Unit 7 Control (field 4)'' – If the unit 7 control should be on select ''yes'', if not select ''no''.
*Hydrograph Control (field 5) – Section designated to control the output of hydrographs.
**"TAPE22 file (22)" – The file read by WMS for the display of hydrographs. This should only be changed to suppress particular hydrographs.
**"TAPE 21 file (21)" – The file used to suppress particular hydrographs.
For each hydrograph station (basin hydrographs, combined hydrographs, and routed hydrographs) different output controls can be specified. This dialog is accessed by selecting the ''Output Control'' dialog button from the ''Edit HEC-1 Parameters'' dialog. Entries which can be defined in this dialog are described below.


===HEC-1 No Precipitation===
===Routed and Combined Hydrographs at Outlets===
If no precipitation for a given basin is chosen, then the program will use the precipitation pattern of the most recently defined basin. In other words, if the same precipitation pattern is to be used for each basin, specify precipitation at the upper-most basin and let all other basins "inherit" this same pattern.


===Basin Average Precip (PB)===
In WMS an outlet point is used to represent locations where hydrographs are both combined and then routed. Therefore, if an outlet is selected before choosing the ''Output Control'' dialog, a radio group at the top of the dialog appears to specify whether the options should be applied to the combined or routed hydrograph. If a basin is selected the radio group at the top of the dialog does not appear.
With this method, a time distribution can be entered to create a PI or PC card. The distribution is entered via the ''XY Series Editor'', refer to the article titled [[WMS:XY Series Editor|XY Series Editor]]. Several standard storm distributions can be loaded automatically from this editor. In addition, distributions can be saved and later restored from a file. When creating PI or PC records, an IN record needs to be defined to specify the beginning time and date of the storm. WMS computes the values for this IN card based on the first time increment in the precipitation (PI or PC) record defined in the ''XY Series Editor''. Because only one IN card defining the precipitation time increment is defined for each raifall distribution, the precipitation time increments defined for a single rainfall series in the ''XY Series Editor'' must all be equal.  The time/date parameters entered on the IT card (in the [[WMS:HEC-1 Job Control|''HEC-1 Job Control'' dialog]]) are used for the start time/date of the precipitation.


===Precipitation Gage (PG)===
==''HEC-1 Precipitation'' Dialog==
Gages can be used with or without a terrain model. If drainage basins have been defined using a TIN, the appropriate gage weights (using the Thiessen polygon method) for each basin are automatically computed when the '''Compute (or Update) Basin Data''' command is executed. If the HEC-1 model is defined using only the tree, or to change any of the computed values, the gage weights can be changed/assigned by clicking on the gage weights button in the ''Precipitation'' dialog. The gage weights dialog will display a list of all defined gages and their station type. Choose from this list when defining gage weights to the selected basin. Storm total stations are written on PT/PW records whereas recording stations are written on PR/PW records. The project must have at least one PR/PW record combination for each basin.
[[Image:HEC1 Precipitation.png|thumb|400 px|''HEC-1 Precipitation'' dialog]]
Precipitation patterns are assigned to basins by first selecting the appropriate basin(s) and then clicking on the '''Precipitation''' button in the ''Edit HEC-1 Parameters'' dialog. If multiple basins are selected then the defined parameters will apply to all selected basins.  


When using a terrain model (DEM, TIN, or Feature Objects) a [[WMS:Rain Gage|rain gage coverage]] can be defined and used to establish the positions of gages by using the graphical creation/selection tools available in the [[WMS:Map Module|Map module.]]
:'''''NOTE:''''' If no basins are selected, the parameters can be applied to all basins.


===Hypothetical Storm (PH)===
Dialog is accessed by selecting ''HEC-1''|'''Edit Parameters...''' in WMS and then choosing '''Precipitation...''' from the ''Edit HEC-1 Parameters'' dialog.
A hypothetical storm may also be used to define the precipitation pattern for the runoff simulation. The [[WMS:XY Series Editor|''XY Series Editor'']] is used to define the necessary rainfall values for the appropriate times. The storm frequency in percent is entered in the frequency edit field. Rainfall will be converted to an annual-series for fifty, twenty, and ten percent storms. No conversion is made for any other frequency storms. A storm area to be used in computing reduction of point rainfall depths is entered in the area edit field. If 0 is entered for the area then the basin area (or area from JD card for depth/area storms) will be used as a default.


===Probable Maximum Precipitation (PM)===
If no precipitation for a given basin is chosen, then the program will use the precipitation pattern of the most recently defined basin. In other words, if the same precipitation pattern is to be used for each basin, specify precipitation at the upper-most basin and let all other basins "inherit" this same pattern.
Defining precipitation using the probable maximum precipitation option allows for the computation of the probable maximum storm according to the outdated Hydrometeorological Report No. 33 (HMR 33). This does use an outdated method and has been retained in HEC-1 for now in order to be able to reproduce results according to the old HMR 33 method.


The following variables must be defined:
''No Precipitation'' – Select if there was no precipitation.
* ''PMS'' – The probable maximum index precipitation from the HMR 33.
''Basin average (PB)'' – Select to specify the Basin Average.
* ''TRSPC'' – Precipitation adjustment (between 0 and 1.0) based on drainage area size. If this value is set at zero HEC-1 will default it to the appropriate value based on the HOP Brook Adjustment Factor as described in the HEC-1 manual.
*''Average precipitation:'' – Enter the average precipitation in inches here.
* ''TRSDA'' – The drainage area in square miles for which the storm is transposed.
*'''Define Series''' – Select to bring up the [[WMS:XY Series Editor|''XY Series Editor'' dialog]].
* ''SWD'' – This value can be set to the EM 1110-2-1411 criteria or the Southwestern Division criteria.
*'''Get Precip From Web''' – Select to bring up the ''Get Online NOAA Atlas 14 Data'' dialog.
* ''R6, R12, R24, R48, R72, R96'' – Maximum precipitation at the specified hourly intervals as a percentage of the probable maximum storm. The ''R48'', ''R72'', and ''R96'' values are optional
''Gage (PG)'' – Gages can be used with or without a terrain model. If drainage basins have been defined using a TIN, the appropriate gage weights (using the Thiessen polygon method) for each basin are automatically computed when the Compute (or Update) Basin Data command is executed.
*'''PT Gage Weights''' – Section where gage weights can be changed/assigned.
*'''PR Gage Weights''' – Section where gage weights can be changed/assigned.
''Hypothetical storm (PH)'' – Select to define the characteristics of a hypothetical storm.
*'''Define Storm''' – Select to bring up the [[WMS:XY Series Editor|''XY Series Editor'' dialog]].
*''Frequency'' – Enter the frequency of a hypothetical storm here.
*''Storm area:'' – Enter the area of the hypothetical storm in mi^2.
''Probable Maximum Precipitation (PM)'' – Allows for the computation of the probable maximum storm according to the outdated Hydrometeorological Report No. 33 (HMR 33).
*''PMS:'' – Enter the probable maximum index precipitation from the HMR 33. Recorded in inches.
**'''% of PMS''' – Click to bring up the ''HEC-1 Percentage of PMS'' dialog.
***''Maximum 6-hour percentage of PMS'' – Maximum amount of probable precipitation inside a 6 hour time period.
***''Maximum 12-hour percentage of PMS'' – Maximum amount of probable precipitation inside a 12 hour time period.
***''Maximum 24-hour percentage of PMS'' – Maximum amount of probable precipitation inside a 24 hour time period.
***''Maximum 48-hour percentage of PMS'' – Maximum amount of probable precipitation inside a 48 hour time period.
***''Maximum 72-hour percentage of PMS'' – Maximum amount of probable precipitation inside a 72 hour time period.
***''Maximum 96-hour percentage of PMS'' – Maximum amount of probable precipitation inside a 96 hour time period.
**'''SWD''' – Click to open the ''Precipitation Distribution'' dialog.
***''EM 1110-2-21411 criteria'' – Represents the standard flood determinations for the project.
***''Southwestern Division criteria'' – Represents the flood determinations for the southwestern division.
*''TRSPC:'' – Precipitation adjustment (between 0 and 1.0) based on drainage area size. If this value is set at zero HEC-1 will default it to the appropriate value based on the HOP Brook Adjustment Factor as described in the HEC-1 manual.
*''TRSDA:'' – The drainage area in square miles for which the storm is transposed.


==Loss Method...==
==''HEC-1 Loss Methods'' Dialog==
[[Image:HEC1 Loss Methods.jpg|thumb|275 px|''HEC-1 Loss Method'' dialog]]
[[Image:HEC1 Loss Methods.png|thumb|400 px|''HEC-1 Loss Method'' dialog]]
One of several different loss methods can be chosen when generating synthetic hydrographs. A loss method is assigned to a basin by first selecting the basin and then choosing the '''Loss Method''' button in the ''Edit HEC-1 Parameters dialog''. As with other basin data the same parameters can be assigned to several basins by selecting multiple basins before accessing the ''Loss Method'' dialog.
Dialog is accessed by selecting ''HEC-1''|'''Edit Parameters...''' in WMS and then choosing '''Loss Method...''' from the ''Edit HEC-1 Parameters'' dialog.


When defining a kinematic wave model, it may be necessary to define a separate set of loss parameters for the two different UK records (generally corresponding to pervious and impervious area). This second set of loss parameters is defined from within the ''Unit Hydrograph Method'' dialog.
''Uniform (LU)'' – Losses are used in conjunction with the uniform (LU) or exponential (LE) loss methods.
 
===Uniform Loss Method (LU)===
This loss method uses an initial value and a uniform value to define infiltration losses. Input parameters are as follows:
*''STRTL'' – Initial rainfall/snow melt loss in inches (mm) for snow free ground.
*''STRTL'' – Initial rainfall/snow melt loss in inches (mm) for snow free ground.
*''CNSTL'' – Uniform rainfall/ loss in inches/hour (mm/hour) which is used after the starting loss ''(STRTL)'' has been satisfied.
*''CNSTL'' – Uniform rainfall/ loss in inches/hour (mm/hour) which is used after the starting loss ''(STRTL)'' has been satisfied.
*''RTIMP'' – Percentage of drainage basin that is impervious.
*''RTIMP'' – Ratio of the drainage basin that is impervious. Values should be less than or equal to 1.
 
''Exponential (LE)'' – Parameters for the exponential loss method are as follows
===Losses (LM)===
Losses are used in conjunction with the uniform (LU) or exponential (LE) loss methods. The parameter descriptions are as follows:
 
* ''STRKS'' – The starting value of the loss coefficient on the exponential recession curve for losses in in/hour (mm/hour) when used with the exponential loss rate (LE) or the uniform melt water loss rate (in/hour) when used with the uniform loss rate (LU).
* ''RTIOK'' – Rate of change of the loss-rate parameter computed as the ratio of ''STRKS'' to a value of ''STRKS'' after ten inches of accumulated loss when used with the exponential loss rate or not used when using the uniform loss rate.
 
===Exponential Loss (LE)===
Parameters for the exponential loss method are as follows:
*''STRKR'' – The starting value of the loss coefficient on the exponential recession curve for rain losses.
*''STRKR'' – The starting value of the loss coefficient on the exponential recession curve for rain losses.
*''DLTKR'' – The amount in inches (mm) of initial accumulated rain loss during which the loss coefficient is increased.
*''DLTKR'' – The amount in inches (mm) of initial accumulated rain loss during which the loss coefficient is increased.
*''RTIOL'' – Parameter computed as the ratio of ''STRKR'' to a value of ''STRKR'' after ten inches (ten mm) of accumulated loss.
*''RTIOL'' – Parameter computed as the ratio of ''STRKR'' to a value of ''STRKR'' after ten inches (ten mm) of accumulated loss.
*''ERAIN'' – Exponent of precipitation for rain loss function that reflects the influence of the precipitation rate on basin-average loss characteristics.
*''ERAIN'' – Exponent of precipitation for rain loss function that reflects the influence of the precipitation rate on basin-average loss characteristics.
*''RTIMP'' – Percentage of drainage basin that is impervious.
*''RTIMP'' – Ratio of the drainage basin that is impervious. Values should be less than or equal to 1.
 
''Green ampt (LG)'' – Green-Ampt infiltration loss parameters are as follows:
===Green & Ampt (LG)===
Green-Ampt infiltration loss parameters are as follows:
*''IA'' – Initial loss (abstraction) in inches (mm).
*''IA'' – Initial loss (abstraction) in inches (mm).
*''DTHETA'' – Volumetric moisture deficit. If this value is 0, then the method reduces to the initial loss equal to IA and a constant loss equal to ''XKSAT''.
*''DTHETA'' – Volumetric moisture deficit. If this value is 0, then the method reduces to the initial loss equal to IA and a constant loss equal to ''XKSAT''.
*''PSIF'' – Wetting front suction in inches (mm). If this value is 0, then the method reduces to the initial loss equal to IA and a constant loss equal to ''XKSAT''.
*''PSIF'' – Wetting front suction in inches (mm). If this value is 0, then the method reduces to the initial loss equal to IA and a constant loss equal to ''XKSAT''.
*''XKSAT'' – Hydraulic conductivity at natural saturation in inches/hour (mm/hour).
*''XKSAT'' – Hydraulic conductivity at natural saturation in inches/hour (mm/hour).
*''RTIMP'' – Percentage of drainage basin that is impervious.
*''RTIMP'' – Ratio of the drainage basin that is impervious. Values should be less than or equal to 1.
Using methods defined by the Maricopa County Flood Control District, Green-Ampt parameters can be [[WMS:Compute GIS Attributes|determined from GIS data layers automatically in WMS]].
''Holtan (LH)'' – Parameters used to define the Holtan loss method:
 
===Holtan (LH)===
Parameters used to define the Holtan loss method:
*''FC'' – Holtan's long term equilibrium loss rate in inches/hour (mm/hour) for rainfall/losses on snow free ground.
*''FC'' – Holtan's long term equilibrium loss rate in inches/hour (mm/hour) for rainfall/losses on snow free ground.
*''GIA'' – Infiltration rate in inches/hour per inch *''BEXP'' (mm/hour per mm *''BEXP'') of available soil moisture storage capacity.
*''GIA'' – Infiltration rate in inches/hour per inch *''BEXP'' (mm/hour per mm *''BEXP'') of available soil moisture storage capacity.
*''SAI'' – Initial depth in inches (mm) of pore space in the surface layer of the soil which is available for storage of infiltrated water.
*''SAI'' – Initial depth in inches (mm) of pore space in the surface layer of the soil which is available for storage of infiltrated water.
*''BEXP'' – Exponent of available soil moisture storage.
*''BEXP'' – Exponent of available soil moisture storage.
*''RTIMP'' – Percentage of drainage basin that is impervious.
*''RTIMP'' – Ratio of the drainage basin that is impervious. Values should be less than or equal to 1.
 
''SCS curve number (LS)'' – The SCS curve number method uses the following parameters:
===SCS Loss Method (LS)===
The SCS curve number method uses the following parameters:
*''STRTL'' – Initial rainfall abstraction in inches (mm) for snowfree ground. If value is 0, then initial abstraction will be computed as:
*''STRTL'' – Initial rainfall abstraction in inches (mm) for snowfree ground. If value is 0, then initial abstraction will be computed as:
::<math>0.2* \frac {(1000-10*CRVNBR)}{CRVNBR}</math>.
::<math>0.2* \frac {(1000-10*CRVNBR)}{CRVNBR}</math>.
*''CRVNBR'' &ndash; SCS curve number for rainfall/ losses on snowfree ground.  
*''CRVNBR'' &ndash; SCS curve number for rainfall/ losses on snowfree ground.  
'''''NOTE:''''' Composite Curve Numbers can be computed automatically when this method for computing losses is chosen and a terrain model is present.  
'''''NOTE:''''' Composite Curve Numbers can be computed automatically when this method for computing losses is chosen and a terrain model is present.  
*''RTIMP'' &ndash; Percentage of drainage basin that is impervious.
*''RTIMP'' &ndash; Ratio of the drainage basin that is impervious. Values should be less than or equal to 1.
 
==Unit Hydrograph Method...==
[[Image:HEC1 Unit Hydrograph Methods.jpg|thumb|400 px|''HEC-1 Unit Hydrograph Methods'' dialog]]
One of several different unit hydrograph methods can be chosen when generating synthetic hydrographs. A method is assigned to a basin by first selecting the basin and then choosing the '''Unit Hydrograph Method''' button from the ''Edit HEC-1 Parameters'' dialog. As with other basin options the same parameters can be assigned to several basins by selecting multiple basins before accessing the ''Unit Hydrograph Method'' dialog.
===Clark Unit Hydrograph (UC)===
The parameters for the Clark method are as follows:
*''T<sub>C</sub>'' &ndash; Time of concentration in hours for the unit hydrograph. Several different equations exist for determining the time of concentration. The list of basin geometric attributes computed automatically when basins have been delineated from a terrain model can be useful in many of these equations. These attributes can be viewed from within the ''Unit Hydrograph Method'' dialog by choosing the '''View Basin Geometrical Attributes''' button. Time of concentration can be computed from one of several equations using these attributes, or by using a time computation coverage. These options are accessed from the [[WMS:Travel Times from Basin Data|Compute Parameters &ndash; Basin Data ]] and [[WMS:Travel Times from Map Data|Compute Parameters &ndash; Map Data]] buttons respectively.
*''R'' &ndash; The Clark storage coefficient in hours.
*''TIME AREA CURVE'' &ndash; The time area curve defines the area of the watershed contributing runoff to the basin outlet as a function of time. This curve is defined by selecting the check box and then activating the ''XY Series Editor'' with the adjacent button. The time area curve can be computed automatically from a TIN (this method will not work for watersheds delineated from DEMs or Feature Objects) using the '''Compute Time Area Curves''' button.
 
===Snyder (US)===
Parameters for the Snyder unit hydrograph are as follows:
*''TP'' &ndash; Lag time in hours. Several different equations have been published to determine the lag time of a basin. Many of these use some of the geometric attributes computed automatically when a terrain model is present. These attributes can be viewed by choosing the '''View Basin Geometrical Attributes''' button. Lag time can be computed from one of several equations using these attributes, or by using a time computation coverage. These options are accessed from the [[WMS:Lag Time and Time of Concentration|Compute Parameters &ndash; Basin Data]] and [[WMS:Lag Time and Time of Concentration|Compute Parameters &ndash; Map Data]] buttons respectively ([[WMS:Lag Time and Time of Concentration|see Computing Travel Times]]).
*''CP'' &ndash; Peaking coefficient.
*''TIME AREA CURVE'' &ndash; The time area curve defines the area of the watershed contributing runoff to the basin outlet as a function of time. This curve is defined by selecting the check box and then activating the ''XY Series Editor'' with the adjacent button. The time area curve can be computed automatically from a TIN (this method will not work for watersheds delineated from DEMs or Feature Objects) using the '''Compute Time Area Curves''' button.


===SCS Unit Hydrograph (UD)===
==''HEC-1 Unit Hydrograph Methods'' Dialog==
Parameters for generating a unit hydrograph using the SCS dimensionless method include:
[[Image:HEC1 Unit Hydrograph Methods.png|thumb|400 px|''HEC-1 Unit Hydrograph Methods'' dialog]]
*''TLAG'' &ndash; SCS lag time in hours. Several different equations have been published to determine the lag time of a basin. Many of these use some of the geometric attributes computed automatically when a TIN is present. Lag time can be computed from one of several equations using these attributes, or by using a time computation coverage. These options are accessed from the [[WMS:Lag Time and Time of Concentration|'''Compute Parameters &ndash; Basin Data''']] and [[WMS:Lag Time and Time of Concentration|'''Compute Parameters &ndash; Map Data''']] buttons respectively.
One of several different unit hydrograph methods can be chosen when generating synthetic hydrographs. A method is assigned to a basin by first selecting the basin and then choosing the '''Unit Hydrograph Method''' button from the ''Edit HEC-1 Parameters'' dialog. As with other basin options, the same parameters can be assigned to several basins by selecting multiple basins before accessing the ''Unit Hydrograph Method'' dialog.


===Kinematic Wave (UK)===
Dialog is accessed by selecting ''HEC-1'' | '''Edit Parameters...''' in WMS and then choosing '''Unit Hydrograph Method...''' from the ''Edit HEC-1 Parameters'' dialog.
Distributed outflow from a basin may be obtained by utilizing combinations of three conceptual elements: overland flow planes, collector channels, and a main channel. These elements can be defined if the kinematic wave option is specified.


The first and second kinematic wave records can be used to distinguish between different properties such as pervious/impervious (grass/pavement). For each record, the following parameters can be supplied.
''Clark (UC)'' &ndash; Clark Method.
*''L'' &ndash; Overland flow length.
*''T<sub>C</sub>'' &ndash; Time of concentration in hours for the unit hydrograph.
*''S'' &ndash; Representative slope.
*''R:'' &ndash; The Clark storage coefficient in hours.
*''N'' &ndash; Manning's roughness coefficient.
*''Define Time Area'' &ndash; The time area curve defines the area of the watershed contributing runoff to the basin outlet as a function of time. Select to bring up the [[WMS:XY Series Editor|''XY Series Editor'' dialog]].
*''A'' &ndash; Percentage of sub-basins area that this record represents (The total of the two records must sum to 100).
*'''Compute Tc and R-Maricopa County''' &ndash; This option is only available when the selection of Green ampt (LG) or Uniform (LU) Loss method in the HEC-1 Loss Methods dialog has been done.
*''Losses'' &ndash; A loss method must be defined for each plane. Choosing the '''Define Loss''' button will present the ''Standard Loss Method'' dialog and allow a method to be chosen and parameters defined.
''Snyder (US)'' &ndash; Snyder unit hydrograph.
*''TP:'' &ndash; Lag time in hours.
*''CP:'' &ndash; Peaking coefficient.
*''Define Time Area'' &ndash; The time area curve defines the area of the watershed contributing runoff to the basin outlet as a function of time. Select to bring up the [[WMS:XY Series Editor|''XY Series Editor'' dialog]].
''SCS dimensionless (UD)'' &ndash; Soil Conservation Services unit hydrograph that contains dimensionless time units and dimensionless discharge units.
*''TLAG:'' &ndash; Lag measured in hours.
''Given unit hydrograph (UI)'' &ndash; A given unit hydrograph determined from a separate analysis. The given unit hydrograph must be derived for the same time interval as is specified on the IT record in the ''Job Control'' dialog.
*'''Define Unit Graph''' &ndash; Select to bring up the [[WMS:XY Series Editor|''XY Series Editor'' dialog]].
*'''Maricope County S-Graph''' &ndash; Select this to bring up the ''S-Graph Option'' dialog.
**''S-Graph Types'' section &ndash; Section that allows the choice of areas within Maricopa County for which an S-Graph will be created.
***"Phoenix Valley" &ndash; Area within Maricopa County.
***"Phoenix Mountain" &ndash; Area within Maricopa County.
***"Desert rangeland" &ndash; Area within Maricopa County.
***"Agricultural" &ndash; Represents the agriculture of Maricopa County.
*Basin area=31.8901  (sq. miles)
**''Basin Lag Time:'' &ndash; Measured in minutes.
**''Computational Time Step:'' &ndash; 15 minutes.
''Kinematic Wave (UK)'' &ndash; Section of the dialog where you can specify the characteristics attributed to the Kinematic Wave Method.
*''First Kinematic Record'' &dash; Section where the first data found regarding the Kinematic Wave Method can be recorded.
**''L:'' &ndash; Represents the Overland flow length (measured in ft).
**''S:'' &ndash; Representative slope (measured in ft/ft).
**''N:'' &ndash; Represents Manning's roughness coefficient.
**''A:'' &ndash; Represents the percentage of sub-basins area that this record represents (The total of the two records must be the sum of 100).
*'''Define Loss''' &ndash; Click to open the [[#HEC-1 Loss Methods Dialog|''HEC-1 Loss Methods'' dialog]].
*''Second Kinematic Record'' &ndash; Section where the second found data regarding the Kinematic Wave Method can be recorded.
**''L:'' &ndash; Represents the Overland flow length (measured in ft).
**''S:'' &ndash; Representative slope (measured in ft/ft).
**''N:'' &ndash; Represents Manning's roughness coefficient.
**''A:'' &ndash; Represents the percentage of sub-basins area that this record represents (The total of the two records must be the sum of 100).
*'''Define Loss''' &ndash; Click to open the [[#HEC-1 Loss Methods Dialog|''HEC-1 Loss Methods'' dialog]].
*''RK'' &ndash; Represents the Kinematic Wave routing.
*''RD'' &ndash; Represents the Muskingum-Cunge routing.
*'''Define Channels''' &ndash; Click to open the [[WMS:Basin HEC-1 Cards#RK/RD Channels Dialog|''RK/RD Channels'' dialog]].
*'''Basin Geometrical Attributes''' &ndash; Select to bring up the [[#Basin Geometric Attributes Dialog|''Basin Geometric Attributes'' dialog]] to define the geometric attributes of the data collected from the Basin.
*'''Compute Parameters-Basin Data''' &ndash; Select to bring up the [[#Basin Time Computation Dialog|''Basin Time Computation'' dialog]] and compute the parameters of the basin data collected.
*'''Compute Time Area Curve(s)''' &ndash; Select to bring up the ''Time Area Parameters'' dialog that allows you to specify the maximum run off distance and interval to determine the time area curve. (Option is only available when ''Snyder (US)'' is selected in the ''HEC-1 Unit Hydrograph Methods'' dialog.)
*'''Compute Parameters-Map Data''' &ndash; Select to determine the parameters of the Map Data.


In addition to the kinematic wave records, collector channels and a main channel must be defined. Either [[WMS:Routing HEC-1 Cards#Kinematic Wave (RK), Muskingum Cunge (RD) and Convex (RV)|kinematic wave (RK) or Muskingum-Cunge (RD)]] routing can be specified by selecting the appropriate radio button. A dialog for defining the channels is accessed by choosing the '''Define Channels''' button. The main channel must be defined, whereas the two collector channels are optional. The following parameters are used for each channel:
==''HEC-1 Snow Melt Data'' Dialog==
*''L'' &ndash; Channel length.
[[Image:HEC1 Snow Melt Data.png|thumb|450 px|''HEC-1 Snow Melt Data'' dialog]]
*''S'' &ndash; Channel slope.
*''N'' &ndash; Manning's roughness coefficient for the channel.
*''CA'' &ndash; Contributing area to the channel.
*''SHAPE'' &ndash; The characteristic shape of the channel.
*''WD'' &ndash; Channel bottom width or diameter.
*''Z'' &ndash; Side slopes if the channel type requires it.


For the main channel, only an eight point cross section as defined with the RC, RX, RY cards can be used.  
Dialog is accessed by selecting ''HEC-1'' | '''Edit Parameters...''' in WMS and then choosing '''Snow Melt Data...''' from the ''Edit HEC-1 Parameters'' dialog.


A flag for routing upstream hydrographs can be specified for the main channel from within this dialog as well.
===Derived Unit Hydrograph (UI)===
A given unit hydrograph determined from a separate analysis can be input using the [[WMS:XY Series Editor|XY Series Editor]]. The given unit hydrograph must be derived for the same time interval as is specified on the IT record in the ''Job Control'' dialog.
==Snow Melt Data...==
[[Image:HEC1 Snow Melt Data.jpg|thumb|400 px|''HEC-1 Snow Melt Data'' dialog]]
When snow needs to be considered in the runoff analysis, snow melt data for a basin needs to be defined. HEC-1 has two different methods for computing snowfall/melt simulations: the Degree-Day method, and the Energy-Budget.
When snow needs to be considered in the runoff analysis, snow melt data for a basin needs to be defined. HEC-1 has two different methods for computing snowfall/melt simulations: the Degree-Day method, and the Energy-Budget.


To define data for a selected basin, choose the '''Snow Melt Data''' button from the ''Edit HEC-1 Parameters'' dialog. The toggle at the top of the dialog turns snow calculations on. For both methods the elevation or zone data, the coefficients, and temperature data must be defined.
To define data for a selected basin, choose the '''Snow Melt Data''' button from the ''Edit HEC-1 Parameters'' dialog. The toggle at the top of the dialog turns snow calculations on. For both methods, the elevation or zone data, the coefficients, and temperature data must be defined.


The Degree-Day method is set up once these parameters have been defined. If the Energy-Budget method is toggled on then the Dew point, Short-wave radiation, and Wind speed data must be defined as well. Losses should be defined when either method is used. These losses are used in conjunction with the LU or LE cards for normal basin losses. The check box at the bottom of the dialog allows losses to be turned on or off for a given simulation.
The Degree-Day method is set up once these parameters have been defined. If the Energy-Budget method is toggled on then the Dew point, Short-wave radiation, and Wind speed data must be defined as well. Losses should be defined when either method is used. These losses are used in conjunction with the LU or LE cards for normal basin losses. The checkbox at the bottom of the dialog allows losses to be turned on or off for a given simulation.


===Elevation Zone Data (MA)===
The number of zones that need to be defined is automatically determined and the appropriate edit fields are unhighlighted. The elevation zone parameters are as follows:
Snow computations are accomplished in HEC-1 using separate, equally incremented, elevation zones within each basin. The number of elevation zones for which data must be defined is determined by specifying the base elevation of zone 1 and zone interval in the appropriate edit fields. The default values correspond to the lowest elevation and the range between the highest and lowest elevation (i.e. one elevation zone). More zones can be created by decreasing the interval, or lower elevations can be excluded from calculations by increasing the base elevation. Once the base elevation and interval are set, elevation zone data is defined by choosing the '''Define MA Data''' button. The number of zones which need to be defined is automatically determined and the appropriate edit fields are unhighlighted. The elevation zone parameters are as follows:
*''AREA'' &ndash; The drainage area associated with this elevation zone.
*''AREA'' &ndash; The drainage area associated with this elevation zone.
*''SNOPACK'' &ndash; The snow pack depth.
*''SNOPACK'' &ndash; The snow pack depth.
*''AVEPRECIP'' &ndash; The normal annual precipitation in inches (mm) for this zone.
*''AVEPRECIP'' &ndash; The normal annual precipitation in inches (mm) for this zone.


Areas for the elevation zones can be computed and supplied automatically using the '''Compute Areas''' button. The elevation fields are not part of the HEC-1 input.
''Compute snow melt runoff'' &ndash; Select to allow the input data related to the amount of runoff produced from melting snow.
*Degree-day &ndash; Section where elevation data is entered.
**Elevation Zone data &ndash; Section where elevation data for each zone is to be entered.
***''Base elevation of zone 1:'' (m) &ndash; Elevation data of zone 1.
***''Zone elevation interval'' (m) &ndash; Allows the entering of a value for the zone elevation interval.
***'''Define MA data...''' &ndash; Select to open the ''Define MA Data'' dialog which allows you to input variables for the elevation (ft), area (mi^2), snow pack (ft), and Average precipitation (in) for each zone.
****'''Compute Areas''' &ndash; Select this to open up the ''Units'' Dialog and specify model units for computation.
**Snow Melt Coefficients &ndash; Section where snow melt coefficients are to be entered.
***''Temp. lapse/zone:'' (F) &ndash; Temperature and zone lapse.
***''Snow melt Coeff:'' &ndash; Value entered for the amount of snow melt in the area.
***''Freezing temp:'' (F) &ndash; Temperature that water freezes.
**Temperature Time Series (MT) &ndash; The temperature time series is entered using the ''XY Series Editor'' where each value corresponds to the air temperature at the bottom of the lowest elevation zone for that interval. The starting date is determined from the IN record values in the edit fields corresponding to the temperature data.
***'''Define MT''' &ndash; Select to define the temperature time series and open the [[WMS:XY Series Editor|''XY Series Editor'' dialog]].
''Energy-budget method'' &ndash; Select to allow the input of time series information.
*'''Define MD...''' &ndash; Represents the Dew point time series (MD). Select to bring up the [[WMS:XY Series Editor|''XY Series Editor'' dialog]].
*'''Define MS...''' &ndash; Represents the Short-wave radiation time series (MS). Select to bring up the [[WMS:XY Series Editor|''XY Series Editor'' dialog]].
*'''Define MW...''' &ndash; Represents the Wind-Speed time Series (MW). Select to bring up the [[WMS:XY Series Editor|''XY Series Editor'' dialog]].
''Snow melt losses (LM) &ndash; Section that allows the input of the amount of loss due to snow melting.
*''STRKS'' &ndash; Measured in inches per hour.
*''RTIOK'' &ndash; Similar to RTIOL for snow melt.


===Radiation===
==''RK/RD Channels'' Dialog==
These three data records (dew point, radiation and wind speed) are only defined for the Energy-Budget method. Like the temperature time series, these three HEC-1 records are defined using the [[WMS:XY Series Editor|XY Series Editor]]. Dates for IN records can be specified using the appropriate edit fields and the beginning time and time increment are defined using the ''XY Options'' dialog from within the ''XY Series Editor''.
[[Image:RK RD Channels Dialog.JPG|thumb|380 px|''HEC-1 RK/RD Channels'' dialog]]
 
Accessed by selecting '''Define Channels''' in the Kinematic wave section of the ''HEC-1 Unit Hydrograph Methods'' dialog.
===Temperature (MT)===
Main Channel RK/RD record
The temperature time series is entered using the ''XY Series Editor'' where each value corresponds to the air temperature at the bottom of the lowest elevation zone for that interval. The starting date is determined from the IN record values in the edit fields corresponding to the temperature data. The starting time and time increment (also part of an IN record) are specified in the [[WMS:XY Series Editor|XY Series Editor]] using the ''XY Options'' dialog.
*Normal Muskingum Cunge Parameters
**''L'' &ndash; Channel length.
**''S'' &ndash; Channel slope.
**''N'' &ndash; Manning's roughness.
**''Shape'' &ndash; Characteristic channel shape.
***''TRAP'' &ndash; Trapezoid.
***''DEEP'' &ndash; Deep.
***''CIRCULAR'' &ndash; Circular.
**''WD'' &ndash; Base width of the channel.
**''Z'' &ndash; Side slope of channel.
**''Use Cross Section'' &ndash; Select to bring up the '''Define Cross Section''' option in this dialog.
***'''Define Cross Section''' &ndash; Select to bring up the [[WMS:XY Series Editor|''XY Series Editor'' dialog]].
''Second RK/RD record (HMS collector)'' &ndash; Select to enter a second RK/RD record.
*''L'' &ndash; Channel length.
*''S'' &ndash; Channel slope.
*''N'' &ndash; Manning's roughness.
*''Shape'' &ndash; Characteristic channel shape.
**''TRAP'' &ndash; Trapezoid.
**''DEEP'' &ndash; Deep.
**''CIRCULAR'' &ndash; Circular
*''WD'' &ndash; Base width of the channel.
*''Z'' &ndash; Side slope of channel.
''Third RK/RD record (HMS collector)'' &ndash; Select to enter a third RK/RD record.
*''L'' &ndash; Channel length.
*''S'' &ndash; Channel slope.
*''N'' &ndash; Manning's roughness.
*''Shape'' &ndash; Characteristic channel shape.
**''TRAP'' &ndash; Trapezoid.
**''DEEP'' &ndash; Deep.
**''CIRCULAR'' &ndash; Circular.
*''WD'' &ndash; Base width of the channel.
*''Z'' &ndash; Side slope of channel.
''Route upstream hydrographs to main channel'' &ndash; Select to route upstream hydrographs to the main channel.


==Related Topics==
==Related Topics==

Latest revision as of 16:06, 14 July 2020

Edit HEC-1 Parameters dialog

When a basin is selected in the HEC-1 model, selecting HEC-1 | Edit Parameters will bring up the Edit HEC-1 Parameters dialog with the Basin HEC-1 Cards section active. The following can then be specified:


HEC-1 Basin Data Dialog

Dialog is accessed by selecting HEC-1 | Edit Parameters... in WMS and then choosing Basin Data... from the Edit HEC-1 Parameters dialog.

HEC-1 Basin Data dialog

Basin name– Each hydrograph station should be identified with a unique name. This name appears as part of the KK record for that station in the input file.

Area – Areas should be entered in either square miles or square kilometers.

Basin Descriptor (Optional) – Option for more Description of the Basin.

Input hydrograph (QI, BI)

  • Direct input hydrograph (QI) – This hydrograph can be input by selecting the checkbox.
  • Define QI – Allows for the definition of the direct input hydrograph. Click to open the XY Series Editor dialog.
  • Tape 21 input hydrograph (BI) – Select to indicate that the data should be input as a general hydrograph.
  • Tape 22 input hydrograph (BI) – Select to indicate that the data should be input as a specific hydrograph.

Observed hydrograph (QO)

Base Flow Parameters – Base flow parameters can be defined for a basin by selecting the Enter base flow checkbox. The input parameters for base flow are as follows:

  • Enter base flow – Select this to enter the defined base flow.
  • STRTQ – Flow at the start of the storm in cfs (cms for metric units).
  • QRCSN – Flow in cfs (cms) below which base flow recession occurs in accordance with the recession constant RTIOR. In other words, it is that flow where the straight line (in semilog paper) recession deviates from the falling limb of the hydrograph.
  • RTIOR – The ratio of the recession flow (QRCSN) to that flow occurring one hour later (Must be greater than or equal to 1).

HEC-1 Output Control Dialog

HEC-1 Output Control dialog

Dialog is accessed by selecting HEC-1 | Edit Parameters... in WMS and then choosing Output Control... from the Edit HEC-1 Parameters dialog.

Comment Lines section – Individual comments can be defined for each hydrograph station. These comments can be used to identify unique characteristics about a particular basin or outlet point.

  • New – Select to add a new comment.
  • Delete – Select to delete an existing comment.

Output Control (KO) – These controls determine what information about a given hydrograph station is written to the HEC-1 ASCII output file.

  • Print Control (field 1) – controls how the data collected is printed.
    • "Use IO record (O)" – Default setting, prints the entire IO record.
    • "Print all output (1,2)" – When selected, prints all output.
    • "Print input and summaries" – When selected, it will just print input and summaries of the data.
    • "Print input data only (4)" – When selected, it will print the input data only.
  • Plot Control (field 2) – Section where plots can be controlled.
    • "Use IO record (O)" – Plots are dependant on the IO record.
    • "No printer plots (1)" – Select if there are no printer plots.
    • "Plot hydrograph (2)" – Select to receive output on the plot hydrograph.
  • Plotting Scale (field 3) – Section to specify the plotting scale.
  • Unit 7 Control (field 4) – If the unit 7 control should be on select yes, if not select no.
  • Hydrograph Control (field 5) – Section designated to control the output of hydrographs.
    • "TAPE22 file (22)" – The file read by WMS for the display of hydrographs. This should only be changed to suppress particular hydrographs.
    • "TAPE 21 file (21)" – The file used to suppress particular hydrographs.

For each hydrograph station (basin hydrographs, combined hydrographs, and routed hydrographs) different output controls can be specified. This dialog is accessed by selecting the Output Control dialog button from the Edit HEC-1 Parameters dialog. Entries which can be defined in this dialog are described below.

Routed and Combined Hydrographs at Outlets

In WMS an outlet point is used to represent locations where hydrographs are both combined and then routed. Therefore, if an outlet is selected before choosing the Output Control dialog, a radio group at the top of the dialog appears to specify whether the options should be applied to the combined or routed hydrograph. If a basin is selected the radio group at the top of the dialog does not appear.

HEC-1 Precipitation Dialog

HEC-1 Precipitation dialog

Precipitation patterns are assigned to basins by first selecting the appropriate basin(s) and then clicking on the Precipitation button in the Edit HEC-1 Parameters dialog. If multiple basins are selected then the defined parameters will apply to all selected basins.

NOTE: If no basins are selected, the parameters can be applied to all basins.

Dialog is accessed by selecting HEC-1|Edit Parameters... in WMS and then choosing Precipitation... from the Edit HEC-1 Parameters dialog.

If no precipitation for a given basin is chosen, then the program will use the precipitation pattern of the most recently defined basin. In other words, if the same precipitation pattern is to be used for each basin, specify precipitation at the upper-most basin and let all other basins "inherit" this same pattern.

No Precipitation – Select if there was no precipitation. Basin average (PB) – Select to specify the Basin Average.

  • Average precipitation: – Enter the average precipitation in inches here.
  • Define Series – Select to bring up the XY Series Editor dialog.
  • Get Precip From Web – Select to bring up the Get Online NOAA Atlas 14 Data dialog.

Gage (PG) – Gages can be used with or without a terrain model. If drainage basins have been defined using a TIN, the appropriate gage weights (using the Thiessen polygon method) for each basin are automatically computed when the Compute (or Update) Basin Data command is executed.

  • PT Gage Weights – Section where gage weights can be changed/assigned.
  • PR Gage Weights – Section where gage weights can be changed/assigned.

Hypothetical storm (PH) – Select to define the characteristics of a hypothetical storm.

  • Define Storm – Select to bring up the XY Series Editor dialog.
  • Frequency – Enter the frequency of a hypothetical storm here.
  • Storm area: – Enter the area of the hypothetical storm in mi^2.

Probable Maximum Precipitation (PM) – Allows for the computation of the probable maximum storm according to the outdated Hydrometeorological Report No. 33 (HMR 33).

  • PMS: – Enter the probable maximum index precipitation from the HMR 33. Recorded in inches.
    • % of PMS – Click to bring up the HEC-1 Percentage of PMS dialog.
      • Maximum 6-hour percentage of PMS – Maximum amount of probable precipitation inside a 6 hour time period.
      • Maximum 12-hour percentage of PMS – Maximum amount of probable precipitation inside a 12 hour time period.
      • Maximum 24-hour percentage of PMS – Maximum amount of probable precipitation inside a 24 hour time period.
      • Maximum 48-hour percentage of PMS – Maximum amount of probable precipitation inside a 48 hour time period.
      • Maximum 72-hour percentage of PMS – Maximum amount of probable precipitation inside a 72 hour time period.
      • Maximum 96-hour percentage of PMS – Maximum amount of probable precipitation inside a 96 hour time period.
    • SWD – Click to open the Precipitation Distribution dialog.
      • EM 1110-2-21411 criteria – Represents the standard flood determinations for the project.
      • Southwestern Division criteria – Represents the flood determinations for the southwestern division.
  • TRSPC: – Precipitation adjustment (between 0 and 1.0) based on drainage area size. If this value is set at zero HEC-1 will default it to the appropriate value based on the HOP Brook Adjustment Factor as described in the HEC-1 manual.
  • TRSDA: – The drainage area in square miles for which the storm is transposed.

HEC-1 Loss Methods Dialog

HEC-1 Loss Method dialog

Dialog is accessed by selecting HEC-1|Edit Parameters... in WMS and then choosing Loss Method... from the Edit HEC-1 Parameters dialog.

Uniform (LU) – Losses are used in conjunction with the uniform (LU) or exponential (LE) loss methods.

  • STRTL – Initial rainfall/snow melt loss in inches (mm) for snow free ground.
  • CNSTL – Uniform rainfall/ loss in inches/hour (mm/hour) which is used after the starting loss (STRTL) has been satisfied.
  • RTIMP – Ratio of the drainage basin that is impervious. Values should be less than or equal to 1.

Exponential (LE) – Parameters for the exponential loss method are as follows

  • STRKR – The starting value of the loss coefficient on the exponential recession curve for rain losses.
  • DLTKR – The amount in inches (mm) of initial accumulated rain loss during which the loss coefficient is increased.
  • RTIOL – Parameter computed as the ratio of STRKR to a value of STRKR after ten inches (ten mm) of accumulated loss.
  • ERAIN – Exponent of precipitation for rain loss function that reflects the influence of the precipitation rate on basin-average loss characteristics.
  • RTIMP – Ratio of the drainage basin that is impervious. Values should be less than or equal to 1.

Green ampt (LG) – Green-Ampt infiltration loss parameters are as follows:

  • IA – Initial loss (abstraction) in inches (mm).
  • DTHETA – Volumetric moisture deficit. If this value is 0, then the method reduces to the initial loss equal to IA and a constant loss equal to XKSAT.
  • PSIF – Wetting front suction in inches (mm). If this value is 0, then the method reduces to the initial loss equal to IA and a constant loss equal to XKSAT.
  • XKSAT – Hydraulic conductivity at natural saturation in inches/hour (mm/hour).
  • RTIMP – Ratio of the drainage basin that is impervious. Values should be less than or equal to 1.

Holtan (LH) – Parameters used to define the Holtan loss method:

  • FC – Holtan's long term equilibrium loss rate in inches/hour (mm/hour) for rainfall/losses on snow free ground.
  • GIA – Infiltration rate in inches/hour per inch *BEXP (mm/hour per mm *BEXP) of available soil moisture storage capacity.
  • SAI – Initial depth in inches (mm) of pore space in the surface layer of the soil which is available for storage of infiltrated water.
  • BEXP – Exponent of available soil moisture storage.
  • RTIMP – Ratio of the drainage basin that is impervious. Values should be less than or equal to 1.

SCS curve number (LS) – The SCS curve number method uses the following parameters:

  • STRTL – Initial rainfall abstraction in inches (mm) for snowfree ground. If value is 0, then initial abstraction will be computed as:
.
  • CRVNBR – SCS curve number for rainfall/ losses on snowfree ground.

NOTE: Composite Curve Numbers can be computed automatically when this method for computing losses is chosen and a terrain model is present.

  • RTIMP – Ratio of the drainage basin that is impervious. Values should be less than or equal to 1.

HEC-1 Unit Hydrograph Methods Dialog

HEC-1 Unit Hydrograph Methods dialog

One of several different unit hydrograph methods can be chosen when generating synthetic hydrographs. A method is assigned to a basin by first selecting the basin and then choosing the Unit Hydrograph Method button from the Edit HEC-1 Parameters dialog. As with other basin options, the same parameters can be assigned to several basins by selecting multiple basins before accessing the Unit Hydrograph Method dialog.

Dialog is accessed by selecting HEC-1 | Edit Parameters... in WMS and then choosing Unit Hydrograph Method... from the Edit HEC-1 Parameters dialog.

Clark (UC) – Clark Method.

  • TC – Time of concentration in hours for the unit hydrograph.
  • R: – The Clark storage coefficient in hours.
  • Define Time Area – The time area curve defines the area of the watershed contributing runoff to the basin outlet as a function of time. Select to bring up the XY Series Editor dialog.
  • Compute Tc and R-Maricopa County – This option is only available when the selection of Green ampt (LG) or Uniform (LU) Loss method in the HEC-1 Loss Methods dialog has been done.

Snyder (US) – Snyder unit hydrograph.

  • TP: – Lag time in hours.
  • CP: – Peaking coefficient.
  • Define Time Area – The time area curve defines the area of the watershed contributing runoff to the basin outlet as a function of time. Select to bring up the XY Series Editor dialog.

SCS dimensionless (UD) – Soil Conservation Services unit hydrograph that contains dimensionless time units and dimensionless discharge units.

  • TLAG: – Lag measured in hours.

Given unit hydrograph (UI) – A given unit hydrograph determined from a separate analysis. The given unit hydrograph must be derived for the same time interval as is specified on the IT record in the Job Control dialog.

  • Define Unit Graph – Select to bring up the XY Series Editor dialog.
  • Maricope County S-Graph – Select this to bring up the S-Graph Option dialog.
    • S-Graph Types section – Section that allows the choice of areas within Maricopa County for which an S-Graph will be created.
      • "Phoenix Valley" – Area within Maricopa County.
      • "Phoenix Mountain" – Area within Maricopa County.
      • "Desert rangeland" – Area within Maricopa County.
      • "Agricultural" – Represents the agriculture of Maricopa County.
  • Basin area=31.8901 (sq. miles)
    • Basin Lag Time: – Measured in minutes.
    • Computational Time Step: – 15 minutes.

Kinematic Wave (UK) – Section of the dialog where you can specify the characteristics attributed to the Kinematic Wave Method.

  • First Kinematic Record ‐ Section where the first data found regarding the Kinematic Wave Method can be recorded.
    • L: – Represents the Overland flow length (measured in ft).
    • S: – Representative slope (measured in ft/ft).
    • N: – Represents Manning's roughness coefficient.
    • A: – Represents the percentage of sub-basins area that this record represents (The total of the two records must be the sum of 100).
  • Define Loss – Click to open the HEC-1 Loss Methods dialog.
  • Second Kinematic Record – Section where the second found data regarding the Kinematic Wave Method can be recorded.
    • L: – Represents the Overland flow length (measured in ft).
    • S: – Representative slope (measured in ft/ft).
    • N: – Represents Manning's roughness coefficient.
    • A: – Represents the percentage of sub-basins area that this record represents (The total of the two records must be the sum of 100).
  • Define Loss – Click to open the HEC-1 Loss Methods dialog.
  • RK – Represents the Kinematic Wave routing.
  • RD – Represents the Muskingum-Cunge routing.
  • Define Channels – Click to open the RK/RD Channels dialog.
  • Basin Geometrical Attributes – Select to bring up the Basin Geometric Attributes dialog to define the geometric attributes of the data collected from the Basin.
  • Compute Parameters-Basin Data – Select to bring up the Basin Time Computation dialog and compute the parameters of the basin data collected.
  • Compute Time Area Curve(s) – Select to bring up the Time Area Parameters dialog that allows you to specify the maximum run off distance and interval to determine the time area curve. (Option is only available when Snyder (US) is selected in the HEC-1 Unit Hydrograph Methods dialog.)
  • Compute Parameters-Map Data – Select to determine the parameters of the Map Data.

HEC-1 Snow Melt Data Dialog

HEC-1 Snow Melt Data dialog

Dialog is accessed by selecting HEC-1 | Edit Parameters... in WMS and then choosing Snow Melt Data... from the Edit HEC-1 Parameters dialog.

When snow needs to be considered in the runoff analysis, snow melt data for a basin needs to be defined. HEC-1 has two different methods for computing snowfall/melt simulations: the Degree-Day method, and the Energy-Budget.

To define data for a selected basin, choose the Snow Melt Data button from the Edit HEC-1 Parameters dialog. The toggle at the top of the dialog turns snow calculations on. For both methods, the elevation or zone data, the coefficients, and temperature data must be defined.

The Degree-Day method is set up once these parameters have been defined. If the Energy-Budget method is toggled on then the Dew point, Short-wave radiation, and Wind speed data must be defined as well. Losses should be defined when either method is used. These losses are used in conjunction with the LU or LE cards for normal basin losses. The checkbox at the bottom of the dialog allows losses to be turned on or off for a given simulation.

The number of zones that need to be defined is automatically determined and the appropriate edit fields are unhighlighted. The elevation zone parameters are as follows:

  • AREA – The drainage area associated with this elevation zone.
  • SNOPACK – The snow pack depth.
  • AVEPRECIP – The normal annual precipitation in inches (mm) for this zone.

Compute snow melt runoff – Select to allow the input data related to the amount of runoff produced from melting snow.

  • Degree-day – Section where elevation data is entered.
    • Elevation Zone data – Section where elevation data for each zone is to be entered.
      • Base elevation of zone 1: (m) – Elevation data of zone 1.
      • Zone elevation interval (m) – Allows the entering of a value for the zone elevation interval.
      • Define MA data... – Select to open the Define MA Data dialog which allows you to input variables for the elevation (ft), area (mi^2), snow pack (ft), and Average precipitation (in) for each zone.
        • Compute Areas – Select this to open up the Units Dialog and specify model units for computation.
    • Snow Melt Coefficients – Section where snow melt coefficients are to be entered.
      • Temp. lapse/zone: (F) – Temperature and zone lapse.
      • Snow melt Coeff: – Value entered for the amount of snow melt in the area.
      • Freezing temp: (F) – Temperature that water freezes.
    • Temperature Time Series (MT) – The temperature time series is entered using the XY Series Editor where each value corresponds to the air temperature at the bottom of the lowest elevation zone for that interval. The starting date is determined from the IN record values in the edit fields corresponding to the temperature data.

Energy-budget method – Select to allow the input of time series information.

Snow melt losses (LM) – Section that allows the input of the amount of loss due to snow melting.

  • STRKS – Measured in inches per hour.
  • RTIOK – Similar to RTIOL for snow melt.

RK/RD Channels Dialog

HEC-1 RK/RD Channels dialog

Accessed by selecting Define Channels in the Kinematic wave section of the HEC-1 Unit Hydrograph Methods dialog. Main Channel RK/RD record

  • Normal Muskingum Cunge Parameters
    • L – Channel length.
    • S – Channel slope.
    • N – Manning's roughness.
    • Shape – Characteristic channel shape.
      • TRAP – Trapezoid.
      • DEEP – Deep.
      • CIRCULAR – Circular.
    • WD – Base width of the channel.
    • Z – Side slope of channel.
    • Use Cross Section – Select to bring up the Define Cross Section option in this dialog.

Second RK/RD record (HMS collector) – Select to enter a second RK/RD record.

  • L – Channel length.
  • S – Channel slope.
  • N – Manning's roughness.
  • Shape – Characteristic channel shape.
    • TRAP – Trapezoid.
    • DEEP – Deep.
    • CIRCULAR – Circular
  • WD – Base width of the channel.
  • Z – Side slope of channel.

Third RK/RD record (HMS collector) – Select to enter a third RK/RD record.

  • L – Channel length.
  • S – Channel slope.
  • N – Manning's roughness.
  • Shape – Characteristic channel shape.
    • TRAP – Trapezoid.
    • DEEP – Deep.
    • CIRCULAR – Circular.
  • WD – Base width of the channel.
  • Z – Side slope of channel.

Route upstream hydrographs to main channel – Select to route upstream hydrographs to the main channel.

Related Topics